2.4. Synthesis of dendrimer functionalized SPIONs
PAMAM dendrimer was coated on the surface of APTES modified SPIONs in two steps according to the previous reports with some modification (Liu, Guo, Jin, Yang, & Wang, 2008; Pan et al., 2007; Tajabadi et al., 2013). In the first step, 10 ml of 5% (w/v) APTES modified SPIONs in methanol was sonicated for 20 minutes. Then, 50 ml of 20% (v/v) methyl acrylate was added dropwise to the stirring solution at room temperature for 24 hrs. The resultant solution was washed with methanol five times and separated with a magnetic magnet. In the second step, 10ml of 50% (v/v) ethylenediamine was added to the purified magnetic nanoparticles and stirred for three h and was then placed in the ultrasonic water bath for one h. The final product was sedimented by a magnetic magnet and washed with methanol five times. After completing the second step, a full generation of dendrimers was formed on amine-functionalized magnetic nanoparticles. These steps were repeated two times to achieve the third generation of dendrimer on SPIONs. Fig 1, demonstrates the schematic representation of the synthesis reaction of SPION-G3.